Over the past five years there have been several attempts to produce template-based or pattern-based parallel programming systems (PPS). These attempts have been characterized by a desire to simplify the production of parallel code and to ensure its correctness, at the possible expense of performance. In this paper we present the CO2P3S system, which addresses many of the shortcomings of earlier systems: the potential for irregularities between the patterns and the code, the lack of pattern extensibility, the lack of system openess and the difficulties involved in incremental performance tuning.